The prize quiz

Bill Bryson won the Aventis Prizes for Science Books last year for his book A Short History of Nearly Everything. He is chair of the judges for this year's awards - a role he is finding a lot less nerve-racking and which involves significantly less writing. The winner of this year's awards will be announced at the Royal Society on May 12. The awards ceremony webcast is at www.royalsoc.ac.uk/live

Each week, a different guest quizmaster sets five questions per day, Monday to Friday. Send us your answers to all 25 questions at the end of the week and the first correct entry out of the hat will win a £100 electronic gift card from Borders (www.bordersstores.co.uk).

C1 Roughly what percentage of the Earth is covered with water?

a) 50%

b) 60%

c) 70%

d) 80%

C2 What percentage of this water is suitable for drinking?

a) 10%

b) 50%

c) 1%

d) 25%

C3 The original Australian 50 cent coin contained what value of silver?

a) 20c

b) A$2

c) 50c

d) 10c

C4 How many orchid seeds would be needed to weigh as much as one grain of wheat?

a) 30

b) 300

c) 3,000

d) 30,000

C5 Which of the following is an ingredient of dynamite?

C5

a) Peanuts

b) Almonds

c) Hazelnuts

d) Walnuts

· Entries must reach Prize Quiz, The Guardian, 119 Farringdon Road, London EC1R 3ER by Wednesday May 18. The winner will be notified on May 20. One entry per person. No purchase necessary. The daily online news quiz is at: guardian.co.uk/quiz